This SAE Recommended Practice is equivalent to ISO Standard 6627 TR.

Differences, where they exist, are shown in the appendix with associated rationale.

This document specifies the dimensional features of commonly used oil control rings having two steel segments (rails) separated and expanded by one steel expander/spacer.

The segments vary in width from 0.4 to 0.6 mm. The assembly width ranges from 2.5 to 4.75 mm. The 4.75 mm width is equivalent to existing 3/16 in applications. Expander design will vary considerably with piston ring manufacturer.

The total circumferential deflection and the piston groove depth should be considered when designing these oil rings to optimize the fit of the ring assembly into the piston groove.

This document applies to oil control rings up through 125 mm for reciprocating internal combustion engines. It may also be used for piston rings of compressors working under similar conditions.